CVE-2026-0398
📋 TL;DR
This vulnerability in PowerDNS Recursor allows attackers to cause denial of service through resource exhaustion or perform DNS cache poisoning attacks. It affects PowerDNS Recursor installations that process malicious DNS zones or CNAME chains.
💻 Affected Systems
- PowerDNS Recursor
⚠️ Manual Verification Required
This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.
Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).
🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.
- Review the CVE details at NVD
- Check vendor security advisories for your specific version
- Test if the vulnerability is exploitable in your environment
- Consider updating to the latest version as a precaution
⚠️ Risk & Real-World Impact
Worst Case
DNS cache poisoning leading to traffic redirection, credential theft, or complete service unavailability due to resource exhaustion.
Likely Case
Increased resource consumption causing degraded DNS resolution performance or temporary service disruption.
If Mitigated
Minimal impact with proper network segmentation, rate limiting, and monitoring in place.
🎯 Exploit Status
Exploitation requires sending crafted DNS queries to vulnerable Recursor instances.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 4.9.0 and later
Vendor Advisory: https://docs.powerdns.com/recursor/security-advisories/powerdns-advisory-2026-01.html
Restart Required: Yes
Instructions:
1. Backup current configuration. 2. Download PowerDNS Recursor 4.9.0 or later from official repository. 3. Stop Recursor service. 4. Install updated package. 5. Verify configuration compatibility. 6. Start Recursor service. 7. Monitor for issues.
🔧 Temporary Workarounds
Rate Limiting Configuration
allImplement query rate limiting to reduce impact of resource exhaustion attacks
# Add to recursor.conf: max-cache-entries=1000000
# Add to recursor.conf: max-negative-ttl=3600
Network Access Control
allRestrict which clients can query the Recursor
# Add to recursor.conf: allow-from=192.168.0.0/16
# Add to recursor.conf: allow-from=10.0.0.0/8
🧯 If You Can't Patch
- Implement strict network segmentation to isolate Recursor from untrusted networks
- Deploy additional monitoring for abnormal resource usage patterns
🔍 How to Verify
Check if Vulnerable:
Check Recursor version: pdns_recursor --version | grep VersionCheck Version:
pdns_recursor --version | grep VersionVerify Fix Applied:
Confirm version is 4.9.0 or later and monitor for abnormal resource usage📡 Detection & Monitoring
Log Indicators:
- Unusually high memory or CPU usage
- Excessive CNAME chain resolutions
- Abnormal query patterns from single sources
Network Indicators:
- Spike in DNS query volume
- Malformed DNS queries
- Queries with crafted zone data
SIEM Query:
source="pdns_recursor" (memory_usage>90% OR cpu_usage>90%) OR query_count>1000/s